Bottom loading polyaxial ball and socket fastener with blocking ring with notched split ring

ABSTRACT

The bottom loading fastening system that consists of the polyaxial ball and socket joint used in conjunction with a bone screw. The system allows attachment to a bone screw using a retaining ring with a blocker ring to assure proper ring positioning. The retaining ring having a continuous inner surface wall and an outer wall having a notch. Upon installation the retainer wall is expanded causing a break at the notch producing an audible and tactile indication that the sufficient force has been applied to set the retainer and blocker rings locking the bone screw to a U-shaped connecting assembly.

PRIORITY CLAIM

In accordance with 37 C.F.R. 1.76, a claim of priority is included in anApplication Data Sheet filed concurrently herewith. Accordingly, thepresent invention claims priority as a continuation-in-part of U.S.patent application Ser. No. 15/839,179 entitled SPRING CLIP BOTTOMLOADING POLYAXIAL BALL AND SOCKET FASTENER filed Dec. 12, 2017incorporated herein by reference.

FIELD OF THE INVENTION

This invention is directed to the field of ball and socket fasteners,and in particular to a polyaxial ball and socket fastener having anotched split ring adapted for use as a spinal implant.

BACKGROUND OF THE INVENTION

There are numerous ball and socket fasteners, however, when theapplication is applied to a particular product, the ball and socket mustmeet minimum specifications in order to be effective. For instance, inthe field of spinal pathologies, the development of spinal fixationdevices represents a major medical breakthrough. Surgically implantedfixation systems are commonly used to correct a variety of backstructure problems, including those which occur as a result of trauma orimproper development during growth. A commonly applied fixation systemincludes the use of one or more stabilizing rods aligned in a desiredorientation with respect to a patient's spine. Anchoring screws areinserted into the patient's spinal bones, and a series of connectors areused to rigidly link the rods and anchors.

A variety of designs exist, with each design addressing various aspectsof the difficulties that arise when one re-shapes an individual's spineto follow a preferred curvature. Known spinal implant systems oftencorrect one set of problems only to create new ones.

Common to all spinal implant systems is the necessity for properanchoring to the bone so as to provide support for the aforementionedcomponents. While bone screws are commonly used for anchoring, the useof a polyaxial design has proven very effective in allowing a surgeonthe flexibility to secure an installation with minimal strain on theindividual.

For this and other reasons, screws located in bone structure typicallyuse a polyaxial base and a specially designed connector member forattachment to a component such as an alignment rod. A problem with thecurrent technology is that bone structure cannot be determined until thepatient's bone is exposed. This problem requires a large inventory ofvarious sized implants to be on hand during every surgery. The surgeonmust search through the inventory to assemble a combination based on hisprediction of what will be required. Even if an implant combination ispredicted, the anchoring screw may still require angular insertion dueto muscle structure or nerve locations. Any movement of muscle and othertissue increases the difficulty of the operation and can be a majortrauma to the patient. Still yet, bone condition may require oversizethreads to achieve a suitable purchase to the bone. As a consequence,the surgeon must either maintain a large inventory of anchoring devices,or have a vendor standing by with a large inventory of anchoring devicesthat will hopefully meet the individual requirements.

One of the problems with a polyaxial pedicle screw is the lack of astabilized angular placement position during installation. Once apolyaxial pedicle screw is inserted into the bone, the connectorcomponent portion has yet to receive a connecting rod leaving theconnector assembly to flop over making it difficult for the Surgeon tograsp while in the midst of surgery. This problem is compounded by theneed to align multiple component heads for receipt of a connecting rod.

U.S. Pat. No. 7,066,937 discloses an apparatus including a housinghaving a first passage configured to receive a longitudinal member and asecond passage with an axis transverse to the first passage; a fastenerextending through an opening in the housing and being moveable relativeto the housing; the second passage of the housing having an indentation,the indentation including an axially extending surface at leastpartially defining the second passage and an upper surface extendingtransverse to the axially extending surface, a spacer received in thesecond passage of the housing, the spacer having a radial surface belowthe upper surface of the indentation; and a member contacting the uppersurface of the indentation and the radial surface of the spacer thatapplies an axial force to the spacer to prevent relative movementbetween the fastener and the housing and holding the fastener in any oneof a plurality of angular positions relative to the housing.

U.S. Pat. Nos. 7,947,065; 8,075,603 and 8,465,065 disclose a polyaxialball and socket joint used in conjunction with a bone screw havingthreads on one end for use in anchoring to the spine and a sphericalconnector on the other end operating as a pivot point about which aconnecting assembly moves in a polyaxial fashion. A substantiallyU-shaped connecting assembly has a lower receptacle that operates as asocket for housing an upper retainer ring and a lower split retainingring. The socket is receptive to the spherical connector which isinserted through the lower split retainer ring causing a momentarydisplacement thereof which allows for the positioning of the sphericalconnector between the upper and lower retainer rings.

U.S. Pat. No. 6,485,491 discloses a multi-axial bone anchor assemblythat includes a saddle member, a bone anchoring member and a washer. Thesaddle has a channel that receives a rod. A snap ring secures the washerin the saddle member. The snap ring engages a snap ring recess. Thedisclosed structure would not prevent relative movement between afastener and housing and would not hold a longitudinal axis of thefastener in any one of a plurality of desired angular positions relativeto a longitudinal of a passage in the housing when a rod, longitudinalmember, is disengaged from a spacer. The patent does not teach anarrangement where a spacer necessarily engages a fastener when a rod,longitudinal member, is so disengaged.

A conventional polyaxial bone screw typically consists of a single shaftwith a coarse thread at one end for threading into the bone. A sphericalball is positioned at an opposite end for coupling to a connectingmember. For example, a number of patents exist for bone screw anchoringassemblies that include a U-shaped connector element which acts as asaddle for attachment to an alignment rod. U.S. Pat. No. 5,133,717 setsforth a sacral screw with a saddle support. Disclosed is the use of anauxiliary angled screw to provide the necessary support in placing thescrew in an angular position for improved anchoring.

U.S. Pat. No. 5,129,900 sets forth an attachment screw and connectormember that is adjustably fastened to an alignment rod. An oblong areaprovided within each connector member allows minute displacement of thealignment rod.

U.S. Pat. No. 4,887,595 discloses a screw that has a first externallythreaded portion for engagement with the bone and a second externallythreaded portion for engagement with a locking nut. The disclosureillustrates the use of a singular fixed shaft.

U.S. Pat. No. 4,946,458 discloses a screw which employs a sphericalportion which is adapted to receive a locking pin so as to allow oneportion of the screw to rotate around the spherical portion. A problemwith the screw is the need for the locking pin and the inability of thebase screw to accommodate a threaded extension bolt.

U.S. Pat. No. 5,002,542 discloses a screw clamp wherein two horizontallydisposed sections are adapted to receive the head of a pedicle screw foruse in combination with a hook which holds a support rod at anadjustable distance.

U.S. Pat. No. 4,854,304 discloses the use of a screw with a top portionthat is adaptable for use with a specially designed alignment rod topermit compression as well as distraction.

U.S. Pat. No. 4,887,596 discloses a pedicle screw for use in coupling analignment rod to the spine wherein the screw includes a clamp permittingadjustment of the angle between the alignment rod and the screw.

U.S. Pat. No. 4,836,196 discloses a screw with an upper portion designedfor threadingly engaging a semi-spherical cup for use with a speciallydesigned alignment rod. The alignment rod includes spaced apartcovertures for receipt of a spherical disc allowing a support rod to beplaced at angular positions.

U.S. Pat. No. 5,800,435 sets forth a modular spinal plate assembly foruse with polyaxial pedicle screw implant devices. The device includescompressible components that cooperatively lock the device alongincluded rails.

U.S. Pat. No. 5,591,166 discloses an orthopedic bone bolt and bone plateconstruction including a bone plate member and a collection offasteners. At least one of the fasteners allows for multi-angle mountingconfigurations. The fasteners also include threaded portions configuredto engage a patient's bone tissue.

U.S. Pat. No. 5,569,247 discloses a multi-angle fastener usable forconnecting patient bone to other surgical implant components. The '247device includes fastening bolts having spherical, multi-piece heads thatallow for adjustment during installation of the device.

U.S. Pat. No. 5,716,357 discloses a spinal treatment and long bonefixation apparatus. The apparatus includes link members adapted toengage patient vertebrae. The link members may be attached in achain-like fashion to connect bones in a non-linear arrangement. Theapparatus also includes at least one multi-directional attachment memberfor joining the link members. This allows the apparatus to be used informing a spinal implant fixation system.

Another type of spinal fixation system includes rigid screws that engagethe posterior region of a patient's spine. The screws are designed withrod-engaging free ends to engage a support rod that has been formed intoa desired spine-curvature-correcting orientation. Clamping members areoften used to lock the rod in place with respect to the screws. Insteadof clamping members, other fixation systems, such as that disclosed inU.S. Pat. No. 5,129,900, employ connectors that join the support rodsand anchoring screws. The connectors eliminate unwanted relative motionbetween the rod and the screws, thereby maintaining the patient's spinein a corrected orientation.

Other spinal fixation systems employ adjustable components. For example,U.S. Pat. No. 5,549,608 includes anchoring screws that have pivotingfree ends which attach to discrete rod-engaging couplers. As a result,the relative position of the anchoring screws and rods may be adjustedto achieve a proper fit, even after the screw has been anchored into apatient's spinal bone. This type of fixation system succeeds in easingthe rod-and-screw-linking process. This adjustment capability allows thescrews to accommodate several rod paths.

U.S. Pat. No. 7,445,627 discloses a fastener and a bone fixationassembly for internal fixation of vertebral bodies. According to oneexemplary embodiment, a tulip assembly is employed, the tulip assemblyincludes a non-circular surface disposed on its outer surface. Afastener is coupled to the tulip assembly and positionable to retain thetulip assembly on the head of a screw. A cap having an outer surface anda plurality of inner protrusions mateably connects to the non-circularsurface on the tulip body to compress the tulip assembly to secure arod.

U.S. Publication No. 2008/0177322 discloses a spinal stabilizationsystem that includes bone fastener assemblies that are coupled tovertebrae. Each bone fastener assembly includes a bone fastener and acollar. The bone fastener has a head portion having at least a firstcross-sectional shape in a first plane, and a second cross-sectionalshape in a second plane. The collar has a circular opening in thebottom, with a relief extending from the circular opening. The secondcross-sectional shape of the bone fastener is keyed to the opening topermit insertion of the bone fastener into the collar assembly from thebottom. After insertion, the bone fastener is rotated to prohibitremoval of the bone fastener from the collar. The collar can then berotated and/or angulated relative to the bone fastener. An elongatedmember can be positioned in the collar and a closure member is then usedto secure the elongated member to the collar.

U.S. Publication No. 2006/0241599 discloses a polyaxial fixation devicehaving a shank with a spherical head formed on a proximal end thereof,and a receiver member having an axial passage formed therein that isadapted to polyaxially seat the spherical head of the shank. Thepolyaxial bone screw further includes an engagement member that isadapted to provide sufficient friction between the spherical head andthe receiver member to enable the shank to be maintained in a desiredangular orientation before locking the spherical head within thereceiver member.

U.S. Publication No. 2006/0235392 discloses a system for connecting afastener element (e.g., a pedicle screw) relative to a rod for thepurposes of vertebral fixation. The system may permit multi-axialmovement between the fastener element and the rod. Further, the systemmay permit the angular relationship between the fastener element and therod to be held in a desired orientation.

U.S. Publication No. 2006/0155277 discloses an anchoring element forsecuring a rod on a vertebra, that comprises a retaining means forreceiving the rod, a safety element placed on the retaining means, asecuring element which can be placed on the body of the vertebra, and aclamping device which is arranged between the retaining means and thesecuring element. The clamping device includes a ring-shaped mount, apartially conical-segment shaped bearing and an intermediate elementwhich is embedded in the mount and which engages the bearing, wherebythe mounting is moveable in a removed state in relation to the bearing,whereas the mount is maintained in a clamped state on the bearing bymeans of the intermediate element. The mount is rigidly connected to theretaining means and the bearing is rigidly connected to the securingelement.

U.S. Publication No. 2006/0149240 discloses a polyaxial bone screwassembly that includes a threaded shank body having an upper capturestructure, a head and a multi-piece retainer, articulation structure.The geometry of the retainer structure pieces correspond and cooperatewith the external geometry of the capture structure to frictionallyenvelope the retainer structure between the capture structure and aninternal surface defining a cavity of the head. The head has a U-shapedcradle defining a channel for receiving a spinal fixation orstabilization longitudinal connecting member. The head channelcommunicates with the cavity and further with a restrictive opening thatreceives retainer pieces and the capture structure into the head butprevents passage of frictionally engaged retainer and capture structuresout of the head. The retainer structure includes a substantiallyspherical surface that mates with the internal surface of the head,providing a ball joint, enabling the head to be disposed at an anglerelative to the shank body.

U.S. Pat. No. 6,716,214 discloses a polyaxial bone screw having a boneimplantable shank, a head and a retaining ring. The retaining ringincludes an outer partial hemispherical surface and an inner bore withradially extending channels and partial capture recesses. The shankincludes a bone implantable body with an external helical wound threadand an upwardly extending capture structure. The capture structureincludes at least one spline which extends radially outward and has awedged surface that faces radially outward therefrom. The capturestructure operably passes through a central bore of the retaining ringwhile the spline passes through a suitably shaped channel so that thespline becomes positioned above the head, at which time the shank isrotated appropriately and the shank is drawn back downwardly so that thespline engages and seats in the capture recess. The head includes aninternal cavity having a spherical shaped surface that mates with thering surface and has a lower restrictive neck that prevents passage ofthe ring once the ring is seated in the cavity.

U.S. Pat. No. 6,565,567 discloses a pedicle screw assembly for use witha rod for the immobilization of bone segments. The assembly is comprisedof a screw, a polyaxial housing for receiving the screw, a washer, a setscrew, and a cup-shaped cap. The lower portion of the housing terminatesin a reduced cross-sectional area, which engages the bottom of the screwhead. When the screw is placed inside the polyaxial housing and thescrew is secured into the bone, the polyaxial housing is pivotable withthree degrees of freedom. The housing includes a top portion with a pairof upstanding internally threaded posts. A washer is inserted betweenthe head of the screw and the rod. A cap, having a bottom, with a pairof posts accommodating openings and a lateral cross connector, is placedover the posts so that the cross connector engages the rod. The crossconnector and washer have concave generally semi-cylindrical rodengaging surfaces to prevent the rod from rotating or sliding within thehousing once the set screw is tightened. A set screw is threaded intothe housing posts to secure the rod within the housing. The washer has aroughened lower surface which, in conjunction with the reducedcross-sectional area at the bottom of the housing, securely clamps andlocks the housing to the screw head when the set screw is tightened.

U.S. Pat. No. 5,501,684 discloses an osteosynthetic fixation devicewhich consists of a fixation element which has a conical head sectionand an anchoring element abutting it which is for attachment into thebone. The fixation device also consists of a spherically formed,layered, slotted clamping piece which has a conical borehole forinstallation of the conical head section, and which is meant for lockingwithin a connecting piece equipped with a spherically shaped layeredborehole. Fixation piece has an axially arrayed tension element,permitting axial displacement and wedging of conical head section in theborehole that corresponds with it. The fixation device is appropriatefor use as a plate/screw system, an internal or external fixator, and inparticular for spinal column fixation.

U.S. Pat. No. 4,693,240 discloses a bone pin clamp for external fracturefixation. The apparatus comprises rotation, slide and housing elementsnested one within the next, each such element having an aperture toreceive a pin there through, and the rotation and slide elementsrespectively affording pin adjustment in azimuth and zenith, and inheight, relative to the housing element. A locking mechanism including acommon actuator member is operable simultaneously to lock the pin androtation and slide elements in the housing element. In a preferred form,the housing element serves as a cylinder with the slide element as akeyed piston therein, and the rotation element is a disc located betweena screw and annular thrust members engaged in the piston, the piston anddisc being split respectively to lock by expansion and compaction underscrew action towards the thrust members.

U.S. Pat. No. 4,483,334 discloses an external fixation device forholding bone segments in known relation to each other. The deviceincludes a pair of bone clamp assemblies each secured to bone pinsextending from the bone segments, a bridge extending between the pinclamp assemblies, and a specialized high friction universal assemblyconnecting the bridge to each of the pin clamp assemblies.

U.S. Pat. No. 4,273,116 discloses an external fixation device forreducing fractures and realigning bones that includes sliding universalarticulated couplings for enabling easy adjustment and subsequentlocking of connections between Steinmann pins and tubular tie-rods. Thecouplings each include a split, spherical adapter sleeve which isembraced by the matching inner surface of an open ring portion of acoupling locking clamp having clamp lugs tightenable against a block bymeans of a nut-and-bolt assembly. Further nut-and-bolt assemblies aredisposed in elongated slots in the blocks and cooperate with associatedclamping members to clamp the Steinmann pins to the blocks afteradjustment in two orthogonal directions and optional resilient bendingof the pins.

U.S. Pat. No. 6,672,788 discloses a ball and socket joint incorporatinga detent mechanism that provides positive biasing toward a desiredposition. The ball and socket joint can be used in flexible supportsthat hold and support items such as lamps, tools and faucets. The detentmechanism comprises two corresponding parts, one in the ball portion andthe second in the socket portion of the joint. The first detent part isa protrusion of some type and the second detent part is a groove orindentation that is adapted to accept and engage the protrusion. If theball contains the detent protrusion, then the socket contains the detentindentation. And conversely, if the socket contains the detentprotrusion, then the ball contains the detent indentation. The detenttensioning force can be provided by a spring or a spring band, thecharacteristics of the material from which the joint is made, or by someother similar tensioning device.

U.S. Publication No. 2003/0118395 discloses a ball and socket joint,which has a housing, a ball pivot mounted pivotably in the housing, anda sealing bellows, which is fastened to the housing and is mounted onthe ball pivot slidably via a sealing ring provided with two legs. Afirst leg of the two legs is in contact with the ball pivot undertension and the second leg meshes with the wall of the sealing bellows.The second leg is, furthermore, fastened in an anchoring ring arrangedat least partially in the wall of the sealing bellows.

U.S. Pat. No. 4,708,510 discloses a ball joint coupling assembly thatpermits universal movement and positioning of an object with respect toa vertical support shaft. Quick release/lock action is provided by aball joint assembly having a housing in which a ball and piston aremovably coupled. The ball is captured between annular jaw portions ofthe housing and piston, with locking action being provided by grippingengagement of the piston jaw portion and the housing jaw portion. Theball member is gripped in line-contact, compressive engagement by theannular edges of the piston jaw and housing jaw on opposite sides of theball. The piston is constrained for axial movement within the housingwith locking engagement and release being effected by rotation of athreaded actuator shaft.

U.S. Pat. No. 3,433,510 discloses a swivel structure for rigidly joiningfirst and second parts together. A first member is connected to thefirst part and a second member is connected to the second part. Anintermediate hollow member interconnects the first and second memberstogether. An enlarged outer end portion is provided on the first memberand includes a plurality of locking means thereon. Means are provided onthe second member for engaging one of the locking means. Means areprovided for threadably joining the hollow member and the second membertogether. A slot is provided in the hollow member and includes anenlarged entrance which passes the enlarged outer end portion and whichalso includes a restricted opening opposite the threaded joining of thehollow member and the second member together. The portion surroundingthe restricted opening opposes the forces imparted against the outer endportion as the second member is threadably joined to the hollow portionand bears against the outer end portion.

U.S. Patent Publication No. 2008/0269809 discloses a bottom loadingpedicle screw assembly. The device includes a pedicle screw and aconnector member. The pedicle screw includes a threaded lower portionwhile the upper portion includes a groove sized to accept a clip member.The clip member includes a spherical outer surface. In operation theclip is placed within the groove and the assembly is pressed through theopening in the bottom of the connector member. While the device isbottom loading, the device will separate when the pedicle screw isaligned with the connector member. The construction of the clip memberallows the clip to collapse sufficiently to pass back through theopening when the screw is positioned in alignment with the connector,requiring the connection to bone be placed at an angle with respect tothe connector for proper operation.

SUMMARY

Briefly, the present invention is a bottom loading polyaxial ball andsocket joint capable of snap together assembly. Disclosed is anexemplary embodiment of the ball and socket fastening system adapted foruse in a spinal fixation system for reshaping the spine of a patient.The fixation system includes the polyaxial ball having a bone screwextending outwardly therefrom for use in anchoring to the spine and aconnector member that includes a socket constructed and arranged toaccept the polyaxial ball. Upon placement of the bone screw, theconnector member can be attached to the bone screw. In the disclosedembodiment, the connector member is illustrated as a U-shaped connectormember having at least one groove at the base of the connector. Thegroove operates as a socket for housing a split ring retainer and ablocker split ring. The U-shaped connector further comprises at leastone cavity or borehole which extends upwards from the junction orinterface between the U-shaped connector and anchor cap into the body ofthe U-shaped connector. The boreholes or cavities can be at an angleless than or equal to 90 degrees with respect to the interface betweenthe anchor cap and U-shaped connector. The interface between the anchorcap and U-shaped assembly is in general, a planar surface. Within thesocket is an anchor cap for receipt of the spherical ball connector. Theanchor cap comprises a planar surface and at least one compressible ornon-compressible member which fit into the one or more cavities orboreholes of the U-shaped connector.

The socket is receptive to the spherical connector which is insertedthrough an aperture in the bottom of the connector assembly where thespherical polyaxial ball contacts the split retainer ring and blockercausing a momentary displacement thereof, allowing the ball to passthrough the ring positioning.

Once the ball has past through the ring positioning, the blocker ringsubstantially encapsulates the retainer ring preventing the retainerring from reopening. The blocker ring essentially removes the spacebetween the outer diameter of the retainer ring and the inner diameterof the spherical connector.

A set screw or nut can then be utilized to press a connecting rod intocontact with the ball while simultaneously causing the lower portion ofthe spherical ball connector to wedge against the inner surface of theconnector member immobilizing the connection.

During surgery a surgeon can determine the most advantageous bone screwor other type of bone connection to match the connecting assembly. Afterinserting the bone screw into the desired location, the bone connectoris then coupled to the connector assembly by inserting or snapping thespherical connector into the socket of the connecting assembly. Inoperation, the spherical connector is pushed past the retainer ringswhereby the rings snap past the largest diameter of the connector toprohibit removal of the connector while still allowing polyaxialmovement between the spherical ball and the connector member. In thepreferred embodiment, the retainer rings are resiliently biased againsta lower and an upper surface of the spherical connector and engage thespherical connector so as to keep the U-shaped connector member inposition during installation. The compressible or non-compressiblemembers of the anchor cap provide further stability so as to keep theU-shaped connector member in position during installation. A surgeon caneasily move the spherical connector member into a preferred position andthe resilient split ring will keep sufficient force between the lowersurface of the spherical connector and the groove so as to maintain thespherical connector in a selected position relative to the connectorassembly. This facilitates the installation of the rod as the U-shapedconnector not only can be rotated into a position for proper placementof the connecting rod but the proper angle of the U-shaped connector canalso be maintained while allowing the surgeon to align additional screwsfor ease of rod placement.

Because of the flexibility and resilience of the retaining rings, themating parts do not require fine tolerances and are economical tomanufacture. The system is modular, employing a collection of anchoringassemblies that are linked, via various connectors, tostrategically-arranged stabilizing rods.

The connector members are rigid structures adapted to link an associatedanchoring assembly with one of the stabilizing rods. The stabilizingrods may be rigid or dynamic members shaped to form aspine-curvature-correcting and/or immobilizing path. Attaching eachanchoring assembly, via connectors, to a stabilizing rod forces apatient's back into a surgeon-chosen shape. Stabilizing rods may be usedsingly, or in pairs, depending upon the type of correction required. Therods vary in size, but typically extend between at least two vertebrae.

Accordingly, it is an objective of the present invention to teach theuse of a bottom loading polyaxial ball and socket fastener for use in aspinal stabilization system utilizing a retainer ring that allowsinsertion of a pedicle screw ball and is then stopped from reopening bya split ring blocker.

Another objective of the invention is to disclose the use of a polyaxialball and socket system that is capable of securing various anchors tovarious connector members so as to reduce the amount of inventoryrequired to meet a particular installation.

It is another objective of the present invention to provide a polyaxialbone screw assembly for a spinal fixation system that permits componentadjustment during installation, thereby enabling satisfactory correctionof a wide variety of spinal deformities.

It is an additional objective of the present invention to provide a bonescrew assembly that includes a split ring locking mechanism that issimple, strong and reliable. Wherein a blocker ring holds a retainerring in place by interference fit between the outer diameter of theretainer ring and inner diameter of the blocker ring.

It is yet another objective of the present invention to provide ablocker ring having a circular shape that approaches 360 degrees ofcoverage around the retainer ring.

Another objective of the invention is to teach the use of a retainerring formed from a 360 degree ring that becomes split when the sphericalhead of a screw is forced through the retainer ring during assembly. Theretainer ring having a notched to provide a tactile feel when the notchis propagated into a split of the retainer ring.

Another objective of the invention to provide a spinal fixation systemthat has an audible sound as well as a tactile feel when the sphericalball causes the retainer ring to split.

Still another objective of the invention to provide a spinal fixationsystem that has a tactile feel wherein the retainer clip snaps intoposition to indicate proper installation.

Other objectives and advantages of this invention will become apparentfrom the following description taken in conjunction with theaccompanying drawings wherein are set forth, by way of illustration andexample, certain embodiments of this invention. The drawings constitutea part of this specification and include exemplary embodiments of thepresent invention and illustrate various objects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is aside view of the U-shaped connector;

FIG. 2 is a cross sectional view of the U-shaped connector and anchorcap;

FIG. 3 is a perspective view of the U-shaped connector;

FIG. 4 is a perspective view of the annulus formed at the distal end ofthe U-shaped connector and grooves therein for receipt of a retainingring;

FIG. 5 is a perspective view of a split-ring;

FIG. 6 is a perspective view of an anchor cap;

FIG. 7 is a perspective view of a compressible member;

FIG. 8 is a perspective view of a split ring constructed and arranged tofit into a retention ring;

FIG. 9 is a perspective view of a retention ring constructed andarranged to receive a split ring of FIG. 8;

FIGS. 10 to 13 are cross-sectional views of the U-shaped connectorillustrating the insertion of the anchor cap;

FIG. 14 is a perspective view of the various sections of the U-shapedconnector;

FIG. 15 is a perspective view of a split ring and a retention ringdisposed in a ring groove of the annulus formed at the distal end of theU-shaped connector;

FIG. 16 is a plane view of the U-shaped connector;

FIG. 17 is a cross-sectional view of the ball and socket fastener withthe anchoring member illustrating the initial step of the insertion of abone screw into the U-shaped connector member;

FIG. 18 is a perspective view of the positioning of the split ring andretaining ring of the assembly in FIG. 17;

FIG. 19 is a cross sectional view of the ball and socket fastener withthe anchoring member illustrating a step in the capturing of the head ofthe bone screw;

FIG. 20 is a perspective view of the positioning of the split ring andretaining ring of the assembly in FIG. 19;

FIG. 21 is a perspective view of the ball and socket fastener with theanchoring member illustrating the cooperation between the spherical balland the connector member;

FIG. 22 is a perspective view of retaining rings illustrating theinteraction between the two retaining rings when the assembly is in thelocked position illustrated in FIG. 21;

FIG. 23 is a perspective view of the ball and socket fastener with theanchoring member illustrating the polyaxial cooperation between thespherical ball and the U-shaped connector member in an unlockedposition;

FIG. 24 is a perspective view of the grooves which accommodate theretaining rings shown in FIG. 22;

FIG. 25 is a perspective view of the retaining rings shown in FIG. 22illustrating the interaction between the two retaining rings when theassembly is in an unlocked position, illustrated in FIG. 23;

FIG. 26 is a perspective view of a set screw;

FIG. 27 is a plane view of the assembled ball and socket fastener;

FIG. 28 is a perspective view of the ball and socket fastener with theanchoring member illustrating the polyaxial cooperation between thespherical ball and the connector member;

FIG. 29 is a perspective view of the second split retainer ring in acontinuous inner side wall position;

FIG. 30 is an enlarged view of a portion of the split ring illustratedin FIG. 29;

FIG. 31 is a perspective view of the second split retainer ring in adetached position; and

FIG. 32 is an enlarged view of a portion of the split ring illustratedin FIG. 31.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While the present invention is susceptible of embodiments in variousforms, there is shown in the drawings and will hereinafter be describeda presently preferred embodiment with the understanding that the presentdisclosure is to be considered an exemplification of the invention andis not intended to limit the invention to the specific embodimentsillustrated.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention.

Definitions

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. Furthermore, to the extent that the terms “including”,“includes”, “having”, “has”, “with”, or variants thereof are used ineither the detailed description and/or the claims, such terms areintended to be inclusive in a manner similar to the term “comprising.”

As used in this specification and the appended claims, the term “or” isgenerally employed in its sense including “and/or” unless the contentclearly dictates otherwise.

For purposes of this disclosure, “proximal” refers to the end closer tothe device operator during use, and “distal” refers to the end fartherfrom the device operator during use.

Device

What is needed in the art, and this invention provides, is a polyaxialball and socket joint that can be adapted for use in a spinal fixationsystem that includes the advantages of known devices, while addressingthe shortcomings that they exhibit. The system should allow componentinterchangeability at point of installation, thereby addressing a widevariety of spinal deformities with less components. In addition, thesystem should allow the stabilized angular placement position of theconnector components during installation.

Referring generally to the Figures, disclosed is an exemplary embodimentof the polyaxial ball and socket fastening system adapted for use in aspinal fixation system. The fastening system includes a spherical ballconnector (18) secured or formed integrally with a bone anchor (12) andconnecting assembly that includes a snap-in type receptacle for thespherical ball connector (18) to form a polyaxial joint allowing a rangeof motion (ROM). The connector assembly (28) also includes a receiverthat may be used in conjunction with a connecting rod member (70) forsecuring at least two bone anchors (12) together.

The bone anchor (12) of the preferred embodiment is a bone anchor (12)including a shank (14) having a length with at least one helical thread(16) formed along the length thereof. It is important to note that theproportions of the bone anchor (12) depicted are for illustrativepurposes only and variations in the length of the shank, diameter of thescrew, thread pitch, thread length, number of thread leads, shankinduced compression and the like may be varied without departing fromthe scope of the invention. At the upper or proximal end (20) of theshank (14) is a ball shaped spherical ball connector (18) having apredetermined diameter. A driver receptacle (22), which may beconfigured as a plurality of recesses or a single recess for aninsertable driver tool, is located along the upper portion (19) of thespherical ball connector (18) for use in installing the bone anchor (12)by use of a driving tool. It should be noted that the driver receptacle(22) may be any shape, male or female, suitable for cooperation with adriving tool to rotate the bone anchor (12) into its final position.

As illustrated in FIGS. 2, 17, 19, 21 and 23, a U-shaped connectorassembly (28) is illustrated having a first retaining ring (40), ablocking ring (40 a) and a second retaining ring (40 b) that isinsertable into a first (30), a second (30 a) and second retaining ringgroove (30 b) respectively. The first retaining ring (40) and secondretaining ring (40 b) are split retaining rings, the blocking ring (40a) is a split ring shaped and sized to snap over the circumference ofthe second split retaining ring (40 b) when the spherical ball connectoris pushed upwards. The blocking ring (40 a) holds the second splitretaining ring (40 b) in place by pinching (interference fit) an outerdiameter of the second split retaining ring (40 b) with an innerdiameter of the blocking ring (40). The blocking ring (40 a) increasesthe width of the cross section as compared with the ring “40 a” setforth in U.S. Pat. No. 9,615,858. The blocker ring (40 a) of the instantinvention provides nearly 360 degrees of coverage for the second ring(40 b), the only coverage not provided is at the split. The retainingand blocking rings (40, 40 a, 40 b), shown in greater detail in FIGS. 5,8, 9, 22 and 25, are made of a biocompatible spring temper materialwhich may include shape memory alloys and in a preferred embodiment isstainless steel.

Referring to FIGS. 29-30, set forth is a preferred embodiment of thesecond split retaining ring (40 b). The second split retaining ring (40b) is further defined by a 360 degree continuous inner surface wall (90)and an outer surface wall (92) with an angular shaped notch (94). Thenotch (94) having a first angular shaped wall (96) adjoining a secondangular shaped wall (98) by an end wall (99). In the preferredembodiment the second split retaining ring (40 b) is formed by acontinuous inner surface wall (90) sized for receipt of the sphericalhead of a pedicle screw during installation. When the spherical head ofa pedicle screw is forced through the continuous inner surface wall (90)the ring (40 b) fractures at the notch (94) to create the split ring asillustrated in FIG. 31. The notch (94) is constructed and arranged tosplit when a predetermined force is applied to the continuous innersurface wall (90) resulting in a tactile feel and an audible sound. Thetactile feel can be felt at the moment of the notch break, and the snapof the ring material provides a sound that can be clearly heard duringthe installation step. The tactile feel and audible sound provide asurgeon with positive reinforcement that the split retainer ring hasbeen pressed against the spherical head of the screw with sufficientforce to cause the spherical head to pass the second split retainer ring(40 b). To further allow for aligning the second split retainer ring (40b) the upper edge (91) of the inner surface wall (90) is chamfered tomeet the outer surface of a spherical ball.

In some embodiments, the U-shaped connector assembly comprises at firstretaining ring (40), preferably a split retaining ring. This isillustrated in FIGS. 10 through 13. As the anchor cap (82) of theU-shaped connector assembly is pushed upwards during the capture of thespherical ball connector (18) (not shown), the first retaining ring (40)expands and slides up the side wall (36) to a displaced position at thesecond annulus (37). Once past the greatest diameter of the sphericalball connector (18) the first retaining ring (40) will contract andslide back down the side wall (36) from its displaced position at thesecond annulus (37) to its normal position along the lower end wall (34)as illustrated in FIG. 12. The spacing of the first split retaining ring(40) within the split ring groove (30) and the material of the firstsplit retaining ring (40) provides a biasing force that ensures that thefirst split retaining ring (40) will not bend as the spherical ballconnector (18) passes the first split retaining ring (40). After thespherical ball connector (18) has been captured by the first splitretaining ring (40), the first split retaining ring (40) will thereafterserve to maintain a slight upward force on the spherical ball connector(18) as the first split retaining ring (40) attempts to contract to adiameter smaller than the diameter (D1) of the first annulus (35). Theupward biasing force created by the first split retaining ring (40)creates a frictional engagement of the spherical ball connector (18)with the lower end wall (34) and the side wall (36) and the lowerportion (17) of the spherical ball connector (18) as illustrated in FIG.13. The split retaining ring provides a tactile feel wherein theretainer clip snaps into position to indicate proper installation. Theretaining ring can also comprise a pressure ring (40′) and a first splitretaining ring (40) wherein the pressure ring (40′) in this embodimentis shown as having a pentagonal shape. The pressure ring captures thesplit retaining during the capture of a spherical ball connector asdescribed above. The assembly is shown in FIGS. 14 and 15.

As illustrated in FIGS. 2, 21 and 23. The U-shaped connector assembly(28) includes an internal passageway (64) that extends from a first ordistal end (66) to a second or proximal end (68). The diameter of theinternal passageway (64) being greater than the diameter of thespherical ball connector (18) at said first end (66) and the diameter ofthe internal passageway (64) at said second end (68) being smaller thanthe diameter of the spherical ball connector (18). The U-shapedconnector assembly (28) includes a base with a pair of U-shaped openingsforming a first upstanding side wall (31) and second side wall (33).

Shown in FIG. 21, the first retaining ring groove (30) is furtherdefined by upper end wall (32), a lower end wall (34) and a side wall(36) therebetween. The side wall (36) is angularly positioned whereinthe junction of the lower end wall (34) and side wall (36) forms a firstannulus (35) having a first diameter (D1) and the junction of the upperend wall (32) and side wall (36) forms a second annulus (37) with asecond diameter (D2), larger than the first diameter (D1).

Shown in FIGS. 21 and 23, the blocking ring groove (30 a) is furtherdefined by upper end wall (32 a), a lower end wall (34 a) and a sidewall (36 a) therebetween. The side wall (36 a) can be vertically orangularly positioned wherein the junction of the lower end wall (34 a)and side wall (36 a) forms a first annulus (35 a) having a firstdiameter (D1 a) and the junction of the upper end wall (32 a) and sidewall (36 a) forms a second annulus (37 a) with a second diameter (D2 a).The second diameter (D2 a) is larger than the first diameter (D1 a) whenthe side wall (36 a) is angularly positioned.

Shown in FIGS. 21 and 23, the second retaining ring groove (30 b) isfurther defined by upper end wall (32 b), a lower end wall (34 b) and aside wall (36 b) therebetween. The side wall (36 b) can be vertically orangularly positioned wherein the junction of the lower end wall (34 b)and side wall (36 b) forms a first annulus (35 b) having a firstdiameter (D1 b) and the junction of the upper end wall (32 b) and sidewall (36 b) forms a second annulus (37 b) with a second diameter (D2 b).The second diameter (D2 a) is larger than the first diameter (D1 a) whenthe side wall (36 b) is angularly positioned.

In embodiments, the diameter (D1 a) of the first annulus (35 a) and thediameter (D2 a) of the second annulus (37 a) of the second groove (30 a)is greater than (i) the diameter (D1 b) of the first annulus (35 b) and(ii) the diameter (D2 b) of the second annulus (37 b) of the secondgroove (30 b). In such an embodiment, the blocking ring (40 a) is largerin diameter than the second retaining ring (40 b) wherein the secondsplit retaining ring (40 b) is positioned around the blocking ring (40a) when the spherical ball connector is pushed upwards so that thesecond groove (30 a) now contains the blocking ring (40 a) and secondsplit retaining ring (40 b) which have expanded to tightly fit into thesecond groove (30 a).

In assembly, the shank (14) of the bone anchor (12) is inserted into thepedicle of a patient by use of a driving tool (not shown), fixing theposition of the bone anchor (12). The U-shaped connector assembly (28)can then be attached over the spherical ball connector (18) of the boneanchor (12), wherein the spherical ball connector (18) engages theretaining and blocking rings (40, 40 a, 40 b). FIG. 23 is a crosssectional view of the spherical ball connector (18) in the process ofassembly to the socket of the U-shaped connector assembly (28) byplacement against the retaining and blocking rings (40, 40 a, 40 b).Referring now to FIG. 21, as the U-shaped connector (28) contacts thespherical ball connector (18), the blocker ring and second split ring(40 a, 40 b), positioned in split ring grooves (30 a, 30 b), contact thespherical ball connector (18) and are moved from their normal positionsalong the lower end walls (34 a, 34 b) to a position along the upper endwalls (32 a, 32 b) respectively. At the widest point of the sphericalball connector (18) contacts the second split retaining ring (40 b), thesecond split retaining ring (40 b) expands in diameter along the upperend wall (32 b) approaching the second annulus (37 b). In this positionthe second split retaining ring (40 b) is able to expand up to thediameter of the blocking ring (40 a) which expands into the diameter (D2a) presented by the second annulus (37 a) allowing the second splitretaining ring (40 b) to pass the spherical ball connector (18) whichallows the U-shaped connector (28) to engage the spherical ballconnector (18). The blocking ring (40 a) exerts an inward force againstthe second split retaining ring (40 b) so that the spherical ballconnector is held in position as the upward biasing force created by theblocking ring and second retaining rings (40 a, 40 b) creates africtional engagement of the spherical ball connector (18) with thelower end wall (34 a) and the side wall (36 a) and the lower portion (17a) of the spherical ball connector (18).

In some embodiments the first retaining ring (40), is a split retainingring. In assembly, once this first retaining ring (40) is past thespherical ball connector (18), the first split retaining ring (40) willcontract and slide back down the side wall (36) from its displacedposition at the second annulus (37) to its normal position along thelower end wall (34), returning to diameter (D1). In this position thefirst split retaining ring (40) prohibits the spherical ball connector(18) from removal, as shown in FIG. 21. The more pressure that isapplied in a removal attempt, the more resistance is provided by thefirst split retaining ring (40) as it is frictionally engaged betweenthe spherical ball connector (18), the lower end wall (34), and thesidewall (36).

The spacing of the first split retaining ring (40) within the split ringgroove (30) and the material of the first split retaining ring (40)provides a biasing force that ensures that the first split retainingring (40) will not bend as the spherical ball connector (18) passes thefirst split retaining ring (40). After the spherical ball connector (18)has been captured by the first split retaining ring (40), the firstsplit retaining ring (40) will thereafter serve to maintain a slightupward force on the spherical ball connector (18) as the first splitretaining ring (40) attempts to contract to a diameter smaller than thediameter (D1) of the first annulus (35). The upward biasing forcecreated by the first split retaining ring (40) creates a frictionalengagement of the spherical ball connector (18) with the lower end wall(34) and the side wall (36) and the lower portion (17) of the sphericalball connector (18). The split retaining ring provides a tactile feelwherein the retainer clip snaps into position to indicate properinstallation.

The anchor cap (82) comprises a first retaining ring (40), which is usedto provide additional stability to the connector assembly during andafter insertion into the bone of a patient. The anchor cap (82) has aspherical surface formed on a lower end (84) which provides a seat forthe spherical ball connector (18), and can be inserted into the internalpassageway of the U-shaped connector assembly (28) to engage with thefirst retaining ring (40) in a first split ring groove (30). The anchorcap (82) seats with and is resiliently biased against an upper portion(19) of the spherical ball connector (18) and engages the spherical ballconnector (18) so as to keep the U-shaped connector assembly (28) inposition during installation. The anchor cap (82) comprises at least onecompressible or non-compressible member (100) which extends from the topof the anchor cap in an upward direction distal to the anchor cap (82)and into a cavity (101) in the U-shaped connector assembly (28). Anexample of a compressible member is a spring. An example of anon-compressible member is a screw. Of course, whether a member iscompressible or non-compressible will also depend on the composition ofthe member, e.g., metal, rubber etc. FIGS. 21 and 23 are cross-sectionalviews of an anchor cap (82). As illustrated in FIGS. 21 and 23, theanchor cap (82) is predominantly cylindrical having an outer surfaceincluding an anchor cap groove (30) for engagement with a firstretaining ring (40) located in a first ring groove (30) on the innerside surface (29) of the U-shaped connector and the outer surface (102)of the anchor cap (82). The anchor cap (82) has a lower end (84) whichis predominantly spherical to engage with and provide a seat for thespherical ball connector (18). As illustrated in FIGS. 21 and 23, as theanchor cap (82), which, is inserted through the bottom of the connectorassembly (28) prior to connecting the connector assembly (28) to a boneanchor (12), the first retaining ring (40) moves from its initialposition along an upper wall of the first ring groove (30) moving up andexpanding outward along a side wall of the first retaining ring groove(32) to a lower wall of the first retaining ring groove (34) and then alower annulus of the first retaining ring groove (34) to allow theanchor cap (82) to pass. When the anchor cap groove (83) and the firstretaining ring groove (30) are in alignment, the first retaining ring(40) will expand, thereby, mechanically connecting the anchor cap (82)to the connector assembly (28). The expansion of the first retainingring (40) provides a biasing upward force on the anchor cap (82) becauseof the angled slope of the anchor cap groove (83). In preferredembodiments, the first retaining ring is a split retaining ring.

A bone anchor (14) can be inserted into the connector assembly (28) fromthe bottom. As the bone anchor (14) is inserted, the first splitretaining ring (40) moves in the split ring groove (30) as describedabove to allow the connector assembly (28) to engage the spherical ballconnector (18). As the spherical ball connector (18) passes the firstsplit retaining ring (40), the upper portion (19) of the spherical ballconnector (18) comes into contact and seats with the lower end (84) ofthe anchor cap (82). The first split retaining ring (40) prevents theanchor cap (82) from disengaging with the connector assembly (28).

Illustrated in FIGS. 21 and 23, the seating of the spherical ballconnector (18) with the anchor cap (82) creates a frictional engagementbetween the upper portion (19) of the spherical ball connector (18) andthe lower end (83) of the anchor cap (82) caused by the downward forceof the anchor cap (82) on the spherical ball connector (18) from thecontraction of the retaining and blocking rings (40, 40 a, 40 b). Thisfrictional engagement between the two surfaces allows the connectorassembly (28) to be positioned and maintained at different angles forinstallation of a connecting rod member (70).

After the anchor cap (82) and spherical ball connector (18) have beeninserted into the connector assembly (28), a connecting rod member (70)and set screw (80) can be inserted to lock the connector assembly (28)together. The set screw (80) exerts a force on the connecting rod member(70) which in turn exerts a force on the anchor cap (82), increasing thefrictional connection between the anchor cap (82) and the spherical ballconnector (18). In this configuration, the spherical ball connector (18)is held more stable by the greater contact surface than without theanchor cap (82) and only the point contact of the connecting rod member(70) on the upper portion (19) of the spherical ball connector (18).

As illustrated in FIG. 28, once mounted the polyaxial action of theU-shaped connector assembly (28) allows for ease of positioning aconnecting rod member (70) into the U-shaped receptacle opening (60). Asecuring element in the form of a set screw (80) is inserted into thethreaded portion (62) of the U-shaped connector assembly (28) until theset screw (80) contacts the connecting rod member (70), causing theconnecting rod member (70) to press against the spherical ball connector(18). The insertion of the securing element causes the spherical ballconnector (18) to wedge the lower portion (17) of the spherical ballconnector (18) against the first split retaining ring (40) therebysecuring the assembly in a desired position. The inner side surface (29)of the anchor cap (82) is generally spherical and constructed andarranged in configuration to be complimentary to the spherical surfaceon the spherical ball connector (18). It should be appreciated that thisconstruction provides a three point contact between the U-shapedconnector assembly (28) and the spherical ball connector (18) bycapturing the connector rod member (70) therebetween with the set screw(80) allowing for securement.

The set screw (80) can have various socket forms for a driverreceptacle, for example, a hex socket, a hexalobular (star shaped)socket, and the like. The socket shape of the set screw (80) is notlimited to these two known patterns and can include others such as asquare/Robertson type socket, pentagon socket, slotted socket, any ofthe cruciform socket types, TTAP socket type, or any other socket typewhich would allow the screw to be securely tightened.

Unique to this invention is the ability for the surgeon to attachvarious types of bone anchors or the like to the connecting assembly,after having installed the bone anchor into the bone of a patient. Whilethere are a myriad of anchoring devices that can be adapted to includethe spherical ball, bone hooks etc., for ease of illustration the bonescrew is depicted and it is well known that various lengths anddiameters of bone screws are available, many of which would not fitthrough the inner diameter of the connector assembly. Thread styles,lengths and so forth that are best suited for installation may beestimated before surgery but it is well known that only during actualsurgery can the proper style be confirmed. Because it is most difficultto predict the proper combination of anchor screw and connector member,surgeons must either have a large selection of spinal implants to choosefrom or be forced to use the closest combination and hope that it willsuffice.

In embodiments, multiple bone anchor (12) sizes can be accommodated by asingle connector assembly (28).

It should be noted that while various types of bone screws have beenmentioned, the instant installation allows placement of an anchoringdevice having a spherical connector into position before a connectormember is attached. This provides the surgeon with an option ofpositioning the bone screw before placement of the connecting memberthereby providing a simplified installation should positioning of theanchoring screw be difficult due to muscle or other interference.Installation of a bone screw with the connecting member allows a rangeof mobility as well as better visual positioning. Further, while theU-shaped connector member is depicted, various types of connectormembers may be used in combination with the spherical ball connector(18) allowing a surgeon to select the appropriate combination duringsurgery thereby enhancing the success for the benefit of the patient aswell as lowering cost of inventory necessary when estimating the varioustypes of situations that the surgeon may encounter during the operation.

All patents and publications mentioned in this specification areindicative of the levels of those skilled in the art to which theinvention pertains. All patents and publications are herein incorporatedby reference to the same extent as if each individual publication wasspecifically and individually indicated to be incorporated by reference.

It is to be understood that while a certain form of the invention isillustrated, it is not to be limited to the specific form or arrangementherein described and shown. It will be apparent to those skilled in theart that various changes may be made without departing from the scope ofthe invention and the invention is not to be considered limited to whatis shown and described in the specification and any drawings/figuresincluded herein.

One skilled in the art will readily appreciate that the presentinvention is well adapted to carry out the objectives and obtain theends and advantages mentioned, as well as those inherent therein. Theembodiments, methods, procedures and techniques described herein arepresently representative of the preferred embodiments, are intended tobe exemplary and are not intended as limitations on the scope. Changestherein and other uses will occur to those skilled in the art which areencompassed within the spirit of the invention and are defined by thescope of the appended claims. Although the invention has been describedin connection with specific preferred embodiments, it should beunderstood that the invention as claimed should not be unduly limited tosuch specific embodiments. Indeed, various modifications of thedescribed modes for carrying out the invention which are obvious tothose skilled in the art are intended to be within the scope of thefollowing claims.

What is claimed is:
 1. A bottom loading connector assembly for polyaxialcoupling to an anchored bone screw having a spherical ball with a shankhaving at least one thread formed along a length of the shank,comprising: a connector assembly having a first side wall and a secondside wall forming a U-shaped opening, a top end and a bottom end with apassageway therebetween having a diameter along the bottom end beinggreater than a major diameter of a bone screw spherical ball and adiameter along the top end being smaller than the major diameter of thespherical ball; a first groove formed along a lower end of saidpassageway; a retaining ring positionable in said first groove, saidretaining ring having a continuous inner surface wall and a notch formedin an outer surface wall; a second groove juxtapositioned to said firstgroove; a blocker split ring positionable in said second groove; ananchor cap dimensioned to fit over a portion of the spherical ball; anda set screw releasably securable to the top end of said connectorassembly; wherein said bottom end of said connector assembly ispositioned over the spherical ball of the anchored bone screw, saidretaining ring and said blocker split ring expands to permit passage ofthe spherical ball whereby said blocker split ring captures saidretaining ring maintaining said retaining ring in position beneath thespherical ball thereby reducing the diameter of the passageway andpreventing removal of said connector assembly from said anchored bonescrew; wherein said retaining ring expands at said notch and snaps intosaid blocker split ring when said spherical ball moves past saidretaining ring in an expanded state, wherein said blocker split ringapplied pressure around a circumference of said retaining ring to assistin positioning said retaining ring along a lower surface of saidspherical ball.
 2. The bottom loading connector assembly for a polyaxialscrew as set forth in claim 1, wherein said blocker split ring is shapedand sized to snap over said retaining ring providing about 360 degreecoverage.
 3. The bottom loading connector assembly for a polyaxial screwset forth in claim 1, wherein said retaining ring is constructed andarranged to indicate a change in diameter by tactile feel and sound whenthe retaining ring is positioned over the spherical ball of the anchoredbone screw.
 4. The bottom loading connector assembly for a polyaxialscrew as set forth in claim 1, wherein a first junction is formed by aside wall of the second groove and a lower end of the second groove, thefirst junction having a first diameter, and a second junction formed bythe side wall of the second groove and an upper wall of the secondgroove, the second junction having a second diameter.
 5. The bottomloading connector assembly for a polyaxial screw as set forth in claim4, wherein said second diameter of said second junction is greater thansaid first diameter of the first junction.
 6. The bottom loadingconnector assembly for a polyaxial screw as set forth in claim 4,wherein said retaining ring can expand in diameter within said secondgroove up to the second diameter of the second annulus as the sphericalconnector is moved past said retaining ring.
 7. The bottom loadingconnector assembly for a polyaxial screw as set forth in claim 1,wherein an internal passageway at said top end of said connectorassembly has a generally spherical surface and is constructed andarranged in configuration to be complimentary to said spherical surfaceof said spherical connector.